A dynamic wrist-hand-finger orthosis or splint is generally used for the positioning of an impaired, injured, or disabled wrist, hand, and fingers. Splints come in a variety of designs: static, static progressive, and dynamic that can be low profile or high profile. Most prior art splints are neurological in nature that either holds the hand in a static functional position, or uses a slight dynamic force to position the fingers.
Many people suffering a neurological injury from stroke, cerebral palsy, brain injury, etc., have upper extremity impairments. Many have some shoulder and elbow movements, but are unable to extend their wrist or fingers to grasp an object. This is usually due to hypertonicity, a condition where the flexor or extensor muscles in the upper extremities are spastic and resist positioning. Dynamic splints can be used to support or to hold joints in certain positions. An effective dynamic splint designed to be used for hypertonicity must offer enough force to balance the effects of the increased muscle tone. Also most current dynamic splints are used for orthopedic injuries and use a variety of finger cuffs to support the digits. These cuffs are not practical when working on a digit affected by hypertonicity, as they move proximal upon closing the fingers, and then have to be repositioned after opening the fingers manually.
Functional electrical stimulation (“FES”) uses electrical currents to activate nerves innervating paretic muscles. The purpose of electrical stimulation is to decrease impairments and increase functional independence. Surface FES systems use controlled electrical currents through electrodes placed on the surface of the body, in order to trigger contraction from muscles underlying the electrode. FES may be used in prostheses for restoring active function to paralyzed or hypertonic body limbs. Unfortunately, with respect to the hand, patients that exhibit increased tone or hypertonicity are unable to effectively use electrical stimulation with or without current orthotics on the market. Neurological patients are unable to adequately extend their fingers, specifically at the PIP and DIP joints, when electrical stimulation is applied. One of the reasons for the lack of finger extension is due to wrist position. As the wrist moves from the flexion to extension, the fingers passively flex. This is phenomenon is called tenodesis. Current FES prostheses do not effectively take wrist position into consideration. Often times, adjusting the wrist position into flexion results in full finger extension when the muscle is stimulated. If finger extension is still lacking following the wrist angle adjustments, then a wrist/hand extension assist mechanism can be applied. Currently, there are no devices available that mechanically extend the wrist and hand while receiving electrical stimulation.
Electrode placement is an important issue for FES since the patient or their caretaker is required to set up the device each time they wish to use it. This involves ensuring that all electrodes are positioned accurately over the motor points of the muscles to be stimulated. Accurate electrode positioning ensures activation of the correct muscle without stimulation delivered to unwanted muscles. Many devices do not offer features that reliably position the electrodes in the correct location in a timely manner.
Thus, there is a continuing need for a neurological rehabilitation device that combines a functional neurological dynamic orthosis (wrist/hand assist or stretching) with electrical stimulation.